||Caption: Dengue virus causes dengue fever and dengue hemorrhagic fever (DHF). The virus is transmitted via mosquitoes primarily from the species Aedes aegypti. A 2001 outbreak in Hawaii was transmitted by Aedes albopictus. Unlike malaria, dengue fever is just as prevalent in urban districts as it is in rural areas. Dengue virus is an RNA virus that belongs to the genus Flavivirus. It belongs to the family Flaviviridae, which includes the hepatitis C virus, West Nile and Yellow fever viruses. Dengue virus is an enveloped virus that possesses cubic capsid symmetry. The principal symptoms of dengue fever are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding. Dengue hemorrhagic fever (DHF) is a severe form of the viral infection. Symptoms of DHF include: persistent vomiting, severe abdominal pain, difficulty breathing, thrombocytopenia, internal bleeding, failure of the circulatory system, shock syndrome, followed by death. Worldwide, 50 to 100 million cases of dengue infection occur each year. The virus has four strains and no specific treatment or vaccine is available. The disease is now endemic in more than 100 countries. Original image courtesy of the CDC.